“Can stainless steel not rust?” This is a bit of black humor, almost let the Chinese Aerospace Science and Technology Group six-engine engine expert, Chen Jianhua, deputy chief designer of the Long March 5 carrier rocket fall into a heart attack.
In the development of China’s 120-ton liquid-oxygen kerosene supplemental combustion engine YF-100, Chen Jianhua noticed that several high-strength stainless steels are prone to rust. Since 2011, he has communicated with his old friend, Su Jie, deputy director of the Special Steel Research Institute of the Iron and Steel Research Institute, and the pressure on both sides is very high.
Today, the Long March 6, No. 7 and No. 5 rockets have made their first flight. Chen Jianhua still has not got a completely convincing answer. He has a piece of foreign engine material, which is still shining in the warehouse for many years.
Strength and rust resistance are contradictory. Steel for rocket engines requires a variety of properties, of which high strength is an important indicator that must be met. Su Jie told the Science and Technology Daily reporter that the austenitic stainless steel used in China’s rocket engines has a yield strength of about 300 MPa, and the material used in the new generation of launch vehicles is two to four times stronger. However, the strength and rust resistance of stainless steel is a contradiction between fish and bear’s paw.
“There is a need to define the concept that stainless steel will rust.” “Simply speaking, the corrosion resistance of steel mainly depends on the content of the alloy element chromium, but if the element is too high, the strength will not go up. Therefore, the anti-rust ability of high strength materials will be poor.
He has a foreign engine material, which is still shining in the warehouse for many years.
To be continued!